Path: utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!srcsip!nic.MR.NET!hal!ncoast!allbery
From: allbery@ncoast.ORG (Brandon S. Allbery)
Newsgroups: comp.unix.wizards
Subject: Re: unix question: files per directory
Message-ID: <13578@ncoast.ORG>
Date: 18 Apr 89 02:00:27 GMT
References: <24110@beta.lanl.gov> <6576@cbmvax.UUCP> <13577@ncoast.ORG>
Reply-To: allbery@ncoast.UUCP (Brandon S. Allbery)
Followup-To: comp.unix.wizards
Distribution: na
Organization: Cleveland Public Access UN*X, Cleveland, Oh
Lines: 24

As quoted from <13577@ncoast.ORG> by allbery@ncoast.ORG (Brandon S. Allbery):
+---------------
| System V has no limit, aside from maximum file size (as modified by ulimit,
| presumably).  As a PRACTICAL limit, when your directory goes triple-indirect,
>--------------------------------------------------------------^^^^^^  HAH!
| it is too slow to search in a reasonable amount of time.  Assuming the
| standard 2K block size of SVR3, this is (uhh, let's see... 2048 bytes/block
| / 16 bytes/dirent = 128 dirent/block; times 10 is 1280 dirent direct, add
| single-indirect = 128 * 512 pointers/block [2048 / 4 bytes/pointer] = 65,536
| entries single-direct; multiply that by 512 to get double-indirect)
| 33,621,248 directory entries before you go triple-indirect.
+---------------

I completely forgot about the inode limit.  System V limits you to 65,535
inodes per file system; as a result, your directory will never go
double-indirect.  However, even single-indirect is noticeably slower than
direct blocks.

++Brandon
-- 
Brandon S. Allbery, moderator of comp.sources.misc	     allbery@ncoast.org
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